Addressing the Cell Purity and Identity Bottleneck Through Generation and Expansion of Clonal Human Embryonic Progenitor Cell Lines
Early Translational I
$4 721 706
Statement of Benefit to California:
This proposal addresses the bottleneck of purity, identity, and safety of a human embryonic stem cell (hESC)-derived cell therapy. Undifferentiated or undefined cell types in the transplanted population may proliferate and differentiate into inappropriate tissues at the site of engraftment or otherwise behave in an unanticipated and unwanted manner. The applicant states that the critical bottleneck is the lack of assays to distinguish the hundreds of embryonic lineages originating out of hESCs and means to purify those cell types to prevent contamination of a therapeutic cellular graft with undesired cell types. This proposal will develop technologies for clonal expansion, purification, and differentiation of human embryonic precursors (hEPCs) (cells capable of proliferation and differentiation into terminally differentiated cell types while expressing transcripts unique to embryonic stages of development) from hESCs. Reviewers concurred that the proposal addresses an unmet need in the field, is innovative, and has sound scientific rationale. If successful, the applicant’s work would benefit the field by providing: 1) a shared bank of standardized good manufacturing practice (GMP)-produced hEPCs with methods for industrial scale up of the lines; 2) peptide and antibody reagents with protocols for identification and isolation of hEPCs; and 3) reagents and protocols for differentiating hEPCs to clinically relevant cells. Reviewers concurred that these resources would help advance stem cell therapies to the clinic. Overall, the reviewers judged the proposal to be feasible, with logical and carefully-planned experiments and a realistic timeline. Reviewers uniformly called the approach innovative. The use of the phage display peptide libraries was felt to be a new and creative means to develop surface markers important in growth and differentiation of hEPCs, and is likely to provide new directions in the field. Another key strength of the proposal are the robust preliminary data, some recently published, concerning the generation of hEPCs, the transcription profiling of these cells, and the isolation of peptides that have different reactivities against some of the hEPCs. Several weaknesses with the proposal were discussed. One major weakness noted by all reviewers is that the marker validation strategy as written uses the same cell populations from which the hEPCs were generated. Reference to a well-characterized primary cell population and any data that the hEPCs have functional capabilites (i.e. can be differentiated into a useful cell type) would be significant improvements in the proposal. The applicant did not detail a rationale or techniques for the teratoma screening, and this was judged to be a minor weakness of the proposal. Finally, one reviewer was dismayed by the number of typographical errors contained in the proposal that detracted from its readability. Reviewers noted the PI to be a well established scientist, one who has made numerous contributions to the stem cell and cell therapy field. One reviewer noted that the PI has committed 25% effort to the project. The collaborations described in this application were judged to be essential for execution of the project, and represented the required diverse expertise. Successful collaborations among these parties in the past reinforced the panel’s confidence in this application. The facilities and resources available to the team were judged to be outstanding. A criticism noted by two reviewers was that the budget was viewed to be excessive, and a large subcontract was not well justified. Animal studies are mentioned in the experimental design, but without budget appropriation. In summary, reviewers felt this to be a strong and cohesive proposal that uses innovative methods to provide novel tools for the isolation of hEPCs, despite a few experimental design considerations. The group is experienced and has been effective in previous collaborations, giving confidence to the panel that the project could potentially alleviate the bottleneck of developing well-characterized and purified precursor cell populations. PROGRAMMATIC REVIEW During programmatic review, the Grants Working Group was instructed to consider the specific rank order of all applications in Tier I as an indicator of priority for funding. A motion was made to move this application up one in the rank order. A panelist cited the application’s potential impact on the field as a reason to increase the funding priority of the application. The motion failed.